Framework Problem: Constructing Engine Mount for Airplane

[MECHIS]

Hi!
I'm currently doing a project where I'm constructing a framework for an engine mount connecting an airplane with an engine. The project involves both calculations by hand and with CAD(Creo), and i have no problem with the CAD part as i have done the simulations.
The part with doing calculations by hand have caused some problems where I'm doing the calculations in 3-D, and its causing some problems.
The top and bottom diagonals are not to be considered in the calculation by hand. Therefore you have 6 symmetrical beams.
So far what I have done in the calculations is that I've created a equation system with help of directional cosines which seems to get me the wrong answers. So I'm looking for some help in creating the equations system for this problem.

 

[Nidum]

I don't understand .

If you take the top and bottom diagonals away then you just have two independent frames .

The three components of anyone of the frames are all in the same plane . For any likely system of loads and fixations the analysis is trivial ?

 

[MECHIS]

View attachment 198290

I don't understand .

If you take the top and bottom diagonals away then you just have two independent frames .

The three components of anyone of the frames are all in the same plane . For any likely system of loads and fixations the analysis is trivial ?

Thanks for the answer Nidium! So what you're suggesting is that we divide the two frames and calculate the forces on one of the pairs, then suggest symmetry?

I also forgot to mention that we have two different forces affecting the framework, one is mg and one is thrust force.

We can't seem to get this right on account of having little knowledge in 3-dimensional calculations.

 

[JBA]

If you are trying to create a composite equation including all elements and loads then you are making the problem more difficult than it needs to be. You would be better off to simply do independent analyses on the different frame structure sections. By transferring the thrust load and the lateral force moment to the back plate then analyzing those loads independently and summing those results the analysis should be straight forward. Since mg is still a force load its components should be able to be combined with static lateral and thrust loads.